1. Field of the Invention
This invention generally relates to an optical reader and an optical scanning system of the type which directs a laser beam from a laser diode package to a symbol for reflection therefrom, and which receives reflected laser light at a discrete photoreceiver located exteriorly of the package and, more particularly, to a compact arrangement in such readers and scanning systems which eliminates the use of and the need for such exterior discrete photoreceivers.
2. Description of Related Art
Various optical readers and optical scanning systems have been developed heretofore to optically read bar code symbols applied to objects in order to identify the object by electro-optically reading the symbol thereon. The bar code symbol itself is a coded pattern comprised of a series of bars of various widths and spaced apart from one another to bound spaces of various widths, said bars and spaces having different light-reflecting characteristics. The readers and scanning systems electro-optically decoded the coded pattern to a multiple alpha-numerical digit representation descriptive of the object. Scanning systems of this general type have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,387,297; 4,409,470; 4,845,350; 4,835,374 and 4,816,660, all of which have been assigned to the same assignee as the instant invention and are incorporated herein by reference thereto.
As disclosed in some of the above patents, a laser light beam was generated by a semiconductor laser diode package. The laser beam was directed at, and repetitively scanned across, a symbol to be read, and then at least a portion of the laser light reflected off the symbol was collected and detected by a photodetector receiver. The photodetector receiver was a discrete component mounted separately from the laser diode package. The photodetector receiver generated electrical analog signals of variable amplitude which corresponded to the variable intensity of the light reflected off the symbol. The analog signals were digitized and decoded into data descriptive of the symbol and, of course, of the object bearing the symbol.
Although the known readers and scanning systems which utilized a separate photodetector receiver were quite satisfactory in terms of performance, such use was disadvantageous in the context of making the reader/scanning system as light in weight, as small in size, as compact, and as inexpensive as possible. It would be desirable, particularly when the reader/scanning system was intended for handheld operation, to eliminate the use of a separate photodetector receiver without sacrificing reader/scanning system performance.